This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Energy harvesting devices and their unique ability to convert the ambient energy into electrical energy have attracted much interest in industrial and manufacturing sectors. Several studies have been done in analysis and development of this technology.
Accordingly, a fan-folded piezoelectric energy harvester is designed to generate electricity using heartbeats vibration. In some embodiments, this energy harvester consists of several bimorph beams stacked on top of each other making a fan-folded shape. In some embodiments, each beam has a brass substrate and two piezoelectric patches attached on both sides of it. These beams are connected to each other by rigid beams. One end of energy harvester 10 is clamped to the wall and the other end is free to vibrate. A tip mass is placed at the free end to enhance the output power of energy harvester 10 and reduce the natural frequency of the system.
High natural frequency is one major concern about the micro-scaled energy harvesters. In some embodiments, the size for this energy harvester is 1 cm by 1 cm by 1 cm, which makes the natural frequency very high. By utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, this natural frequency is reduced to the desired range.
In some embodiments, the generated electricity can be used to power a pacemaker. If enough electricity is generated, the pacemaker operates with a smaller backup battery or none at all, and the patient does not need to have a surgery every seven to ten years due to battery depletion.
Vibration is one of the common sources in energy harvesting. Some conventional sources have studied compact magnetic power generators using different sources of energy, including vibration. One commonly used method of converting vibration into electricity is by using piezoelectric materials. The piezoelectric effect converts mechanical strain into electric current or voltage. A piezoelectric material generates a small voltage whenever it is mechanically deformed. Using vibration and piezoelectric effect has been investigated by numerous groups. There were some studies on energy harvesting using vibration from flying birds or insect flights. Using the weight of passing cars or human weight is another way of generating electricity from piezoelectric beams.
There were some studies in finding the mode shapes of discontinues devices. Wickenheiser, in his research, uses transfer matrices to find the mode shapes of beam structures with pointwise discontinuities.
According to the principles of the present teachings, a new zigzag microstructure is provided that lowers the natural frequency of the system comparing to cantilevered beam. The present teachings introduce linear and nonlinear piezoelectric devices to recharge the batteries of the pacemakers continuously. Energy harvester 10 converts the vibrations from the heartbeats to electrical energy needed for powering the battery.
According to the present disclosure, a fan-folded structure is provided and studied. The free vibration modes for a seven beam structure are found. Other theoretical results were used to verify the method. A tip mass added to energy harvester 10 to decrease the natural frequency of the system and increase the output generated power was provided. The effect of the link masses is also considered in the calculation to have more accurate results. An electromechanical model for vibration and energy harvesting characteristics of energy harvester 10 is presented. The power generated from heartbeat acceleration is calculated for energy harvester 10. The generated power can be used to power a pacemaker. Although the power required for a pacemaker is very low (about 1 after few years, patients require another surgical operation to replace their pacemaker depleted battery. This energy harvester could also be built in larger scale and replace the battery in portable devices, such as cellphones or generate electricity for wireless sensors.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.